- This qualitative study involved in-depth interviews with 13 pregnant and postpartum women to elicit their views about participating in four hypothetical Zika virus vaccine trials
- Most women highly valued evidence and pointed to it as a primary motivator of their decision to agree or decline to participate in vaccine trials
- For some women, information that a vaccine was safe in pregnant animals and nonpregnant humans was persuasive, but for others, the lack of evidence specific to pregnant women was more salient
- Nearly all participants said their major or sole concern was the risk of harm to the fetus, not to themselves
- In general, the women expressed trust in doctors and vaccines
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Pregnant women have historically been excluded from vaccine development, an issue of concern during influenza, Zika and Ebola epidemics and now COVID-19. A recent expert consensus paper from the PREVENT Working Group, published in Vaccine, offers guidance about how pregnant women could ethically be included in vaccine trials, but little is known about what might influence them to participate.
In response to the 2015–2016 Zika epidemic, researchers at Massachusetts General Hospital asked 128 pregnant and postpartum women about their willingness to join trials of hypothetical Zika vaccines. Quantitative survey data, previously reported in Vaccine, indicated that up to 68% were willing to participate.
In a second report from the study, also published in Vaccine, Ilona Goldfarb, MD, MPH, maternal-fetal medicine specialist in the Department of Obstetrics and Gynecology at Massachusetts General Hospital, and colleagues identified three main themes that informed women's decisions about participating in vaccine trials during pregnancy: evidence, risk and trust.
The qualitative data come from in-depth interviews with 13 of the 128 study participants. All were pregnant or within one year postpartum and received care at Mass General between May and August 2017.
Interviewers asked the participants to assume they were at high risk of Zika. They elicited the women's views on joining or continuing trials in four hypothetical scenarios:
- Inactivated vaccine while pregnant—assume another inactivated Zika vaccine was previously found to be safe and effective in a small number of nonpregnant people
- Inactivated vaccine—assume you were found to be pregnant two weeks before the second dose was due; assume that pregnant women were ineligible for the trial, even though the vaccine mechanism has been well tolerated by pregnant women in the past
- Live vaccine while pregnant—assume the vaccine was previously found to be safe and effective in pregnant animals and nonpregnant people
- Nucleic acid vaccine while pregnant—assume the vaccine was previously found to be safe and effective in pregnant animals and nonpregnant people (DNA vaccine platforms have never been tested in pregnant women)
In general, women highly valued evidence and pointed to it as a primary motivator of their willingness or unwillingness to join trials. For some, the fact that a vaccine was safe in pregnant animals and non-pregnant humans was persuasive, but for others, the lack of evidence specific to pregnant women was more salient.
Many participants indicated that evidence on inadvertently vaccinated pregnant women would influence their responses. Some women expressed altruistic motivations to participate in a trial, citing the importance of evidence in pregnancy.
Nearly all participants said their major or sole concern was the risk of harm to the fetus, not to themselves. Some explicitly wanted to identify the option that minimized harm to the fetus alone. Perceived sources of risk varied between women; the most important risks were the vaccine, the virus, pregnancy and the ''unknown unknowns."
Some women said they would trust their doctor's opinion when deciding, although one emphasized a doctor's recommendation would not change her reticence. Similarly, while some women expressed faith in vaccines generally, another noted her concerns, which were driven by negative media coverage.
Several women described a lack of trust in government recommendations about vaccine trial participation. One woman said she would make her decision based on prayer.
Lessons for Researchers
Investigators should anticipate vaccine hesitancy among pregnant women and mitigate it by gathering robust pregnancy-specific human evidence. Likewise, they should follow women inadvertently vaccinated in the periconception period during vaccine trials or rollouts, then make a carefully contextualized analysis readily available.
Within pre-approved parameters determined by ethics committees, investigators should give women safety information that allows them to make complex, values-driven risk–benefit calculations. This may require adapting the informed consent process.
Refer a patient to the Department of Obstetrics & Gynecology
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